PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

When SWC emits const enum metadata as an object for a query parameter type, SchemaObjectFactory#createQueryOrParamSchema() treats that object as a literal object schema. That produces nested property metadata instead of an OpenAPI enum schema for the parameter.

Issue Number: Fixes #3909

What is the new behavior?

createQueryOrParamSchema() now recognizes const-enum-like object metadata before the generic object literal branch and emits a parameter schema with type and enum values.

A regression test covers a query parameter whose type is a const-enum-style object.

Does this PR introduce a breaking change?

• Yes
• No

Other information

Local checks:

• npm test -- test/services/schema-object-factory.spec.ts
• npm run build
• npm run lint (passes with existing warnings outside this change)
• git diff --check